One is the pseudonym of a Japanese manga artist, best known for his web manga series One-Punch Man, which was later remade as a digital manga illustrated by Yusuke Murata. One serialises One-Punch Man on his own website under no official publisher, while the manga remake is serialized in the web version of Weekly Young Jump. His other well-known series, Mob Psycho 100, was serialized in the online version of Weekly Shōnen Sunday, called Ura Sunday.
As of December 2015, his website gets more than 100,000 hits a day, and has logged more than 70 million total visits.
He was born in Niigata and grew up in Kōnosu, Saitama.